Preheat oven to 350°F. Peel parsnips and chop into 1/2-inch chunks. In a large pot, over medium-high heat, melt butter; add brown sugar and salt, and stir together. Let cook 4-5 minutes until bubbling. Add water, stir. Stir in parsnips to coat. Cook, over medium heat, stirring occasionally, 15-20 minutes until parsnips begin to soften and turn a caramel colour. Meanwhile, make crumble topping: In a food processor bowl, pulse together flour, brown sugar, cinnamon and salt. (Or if mixing by hand, just stir together in a mixing bowl.) Add butter and pulse until the size of large peas. Remove from processor and stir in rolled oats. (By hand, cut the butter into the mixture with a pastry blender or 2 forks, then add oats.) Place in freezer until ready to use.
Next, prepare apples. Do not peel, but core and chop into 1/2-inch chunks. Place in large bowl. Toss with cornstarch, spices, salt and vanilla extract. Add caramelized parsnips and toss. Place parsnip-apple mixture in a greased 9" x 14" casserole dish. Generously spoon on crumble topping. You will have more than enough (freeze the remainder for another time). Bake for about 35 minutes until brown and bubbly. Spoon out portions and serve with ice cream, whipped cream or Glenview’s Finest Scald cream!